Abstract:

Objective　To provide anatomic basis for lag screw placement internal fixation in anterior column of acetabular bone via kocher-langenback surgical approach.　Methods　(1)50 adult hip bones (32 males, 18 females) were observed and measured the direction of the long axis of acetabular anterior column, and then the point where the long axis penetrated the outside of the iliac wing was set as the entering point. A guiding pin (3.5mm in diameter) was inserted in the entering point along the long axis, and the penetration was below the pubic tubercle. α angle between the guiding pin and the sagittal plane, and β angle between the pin and coronal plane, the length of the longitudinal axis, the "weak zone" where the guiding pin may easily penetrated bone cortex, and the distance from the penetration point to the pubic tubercle, were measured and analyzed. (2) 34 cadaveric specimens were dissected to explore the distribution of the vessels and nerves around the entrance point of the guiding pin. The screw fixation of the anterior column was simulated and confirmed by X-ray and CT.　Results　The screw entrance point was at the intersection between the line from tubercle of iliac crest to the middle of the ischial tuberosity and the line from anterior superior iliac spine to greater sciatic notch vertex. The exit point of the screw was（6.62±2.79）mm and（11.71±1.66）mm below the pubic tubercle in male and female respectively. α angle was about （51.29±3.48）°, while β angle (22.32±3.66）° in males and（19.57±2.07）° in females, respectively. The length of longitudinal axis of the acetabular anterior column was（108.64±5.49）mm in males and（100.92±6.25）mm in females, respectively. All data presented remarkable sexual significance except for α angel. The simulated fixation showed satisfied effects.　Conclusions　It is convenient and safe to place the lag screw to fix the anterior column while fix the posterior column via kocher-langenback surgical approach in case of compound fracture of both anterior and posterior columns of acetabular bone.

Key words: Acetabular bone, Anterior column, Lag screw；internal fixation, Applied anatomy